Point of Impact at 25 yards for a 100 yard Zero

[Rocketvapor]

Think of it this way.
With 1/4 MOA turrents;
1 MOA is roughly an inch @ 100 yds. Want to move up an inch, 4 clicks.
1 MOA is roughly 1/4 inch @ 25 yds. Want to move up an inch, 16 clicks.

 

[whatsupdoc]

I get that. But you might be surprised how many shooters do not have that solid a good grasp on angular measurements versus linear measurements. My suggestions was for those folks because the number of "clicks", in other words, the amount of linear distance at the target face, changes as the distance decreases below or above 100 yards. So what I stated is spot on. Not everyone that might try to sight in at shorter distances may know or recall that one MOA subtends an arc of 1.0472" at 100 yd, but only 0.5236" at 50 yd, and 0.2618" at 25 yd. My point was that moving the POI a given linear distance on the target face at 50 yards requires twice the number of "clicks" it would at 100 yd, and at 25 yd would require four times the number of "clicks" necessary at 100 yd.

100% correct, I use mostly FFF mil scopes so there is no converting of anything. Sighting in is shoot a round measure correction required with the reticle, input correction to turrets you are zeroed in 3 to 5 shots.

 

[MisterHelix]

I find that with a 100 yard zero, I’m usually 2.5” low at 25 yards, which is basically height-over-bore. This is for scoped rifles or tall .mil irons.

If you use these printable Palma targets, there’s a mark at 2.5”, so that’s what I use for really rough zero, to get on paper. Then I walk out to 100 to refine the zero.

 

[Rocketvapor]

What's the caliber, bullet, etc. ?
I assume it's an AR with maybe 2.7" sight above bore?

 

[MisterHelix]

What's the caliber, bullet, etc. ?
I assume it's an AR with maybe 2.7" sight above bore?

If you’re asking me, the info holds true for my AR’s, but I chose the above target shot with a .308 to more closely match the OP’s rifle. I don’t shoot 6.5 but really I think the answer is similar regardless.

 

[jelenko]

To the first order, the bullet is on a straight line from the muzzle to intersect the point of aim.
So, the point of impact at 25 yards is 1/4 the 'up' to what ever distance of the sights are above the center of the bore.
For example, the center of my scope on my ar is ~ 3" above the center of the bore. To be zeroed at 100 yards, the bullet will impact a target at 25 yards ~ 2 1/4" below the center of the target.
Said another way, its 1/4 [25 yards/100 yards] of the 3" up from 3" [the distance the center of the scope is above the center of the bore] below the center of the target.

 

[Rocketvapor]

Most bullets have DROP from the muzzle to 100yards.
Real drop, not perceived rise from the scope view.
An AR with a high sight radius, 2.5 to 2.7" will show a bigger difference between a 25 yard zero and a 100 yard zero.

Here's some JBM calculations for a 220gr, 486G1 308 with a muzzle velocity of 2800fps.
Bore centerline no sight height, 1.5" sight height, and 2.5" sight height.
What about longer ranges? Same Bullet/Speed.
MOA this time.

 

[cinch29433]

Sight in for 25 and you will be at least 3.5” high at 100 with most scope/ring setups. You can click down 3 moa on your scope and be close or leave it and be on at 300.

Before scope clicking became the norm this is how we sighted in hunting rifles. Many NY hunters would arrive in camp sighted for 200 and we would have them shoot a one holer at 25 to make sure they were ready for 300.

Good luck

 

[Kracken McGraw]

I really don’t understand messing with 25 yards at all with that caliber.
25 yards has really never showed me correct horizontal further out.

 

[Rocketvapor]

I think the only reason to START @ 25 is to get on paper with a new set up.
I can usually boresight to be on paper @ 100.